Sound suppressing mounting for electric induction apparatus



April 4, 1967 "r. J. TWOMEY 3,312,920

SOUND SUPPRESSING MOUNTING FOR ELECTRIC INDUCTION APPARATUS Filed March 19, 1965 F/BJ.

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United States Patent 3,312,920 SOUND SUPPRESSING MOUNTING FOR ELEC- TRIC INDUCTION APPARATUS Thomas J. Twomey, Rome, Ga., assignor to General Electric Company, a corporation of New York Filed Mar. 19, 1965, Ser. No. 441,030 7 Claims. (Cl. 336-100) My invention relates to sound-suppressing mountings for electric induction apparatus, and particularly to means for mounting dry-type electric transformers in such a manner that transmission of vibration from the magnetic parts to the housing walls is minimized.

It has been prior practice to construct air-insulated dry-type power transformers in a housing having an open bottom end adapted to be seated directly upon a suitable foundation. Ordinarily, such a housing is constructed upon a planar base formed as an open frame grid of strong structural bar and channel members. The base grid is positioned substantially in the plane of the open end of the housing and lies flatwise directly upon the foundation. Both the housing and the magnetic core and coil structure have been mounted directly upon the base structure and are thereby directly structurally connected to each other. The mass of the core and its mode of vibration is often such that even though resilient buffer material such as rubber blocking is interposed between the core and the base frame, the base structure transmits an objectionable amount of vibration to the sidewalls. These sidewalls, being formed of rather large area sheets of steel or other metal, generate objectionable noise as a result of their vibration.

Accordingly, therefore, it is a general object of my invention to provide an improved noise-suppressing mounting for heavy electric induction apparatus.

It is a further object of my invention to provide an improved noise-suppressing mounting for ventilated drytype electric power transformers adapted to be mounted upon a massive and rigid foundation structure.

It is a more particular object of my invention to provide a mounting structure for ventilated dry-type electric transformers which substantially eliminates the transmission of vibration from the transformer core to the housing base structure or sidewalls.

In carrying out my invention in one preferred embodimentI provide an electric induction apparatus having a core provided with spaced-apart mounting feet. A cross bar connected between the mounting feet rests upon a bearing pad seated directly upon a massive concrete foundation. The apparatus housing rests independently upon the same foundation, and slidable positioning means between the core and housing provide means to fixedly connect the parts together for rigging or shipment.

My invention will be more fully understood and its new and novel features further appreciated by referring now to the following detailed specification taken in conjunction With the accompanying drawing in which:

FIG. 1 is a fragmentary perspective view of a transformer and housing assembly mounted upon a foundation and having one sidewall removed to show internal mounting structure characteristic of prior art devices; and

FIG. 2 is a fragmentary perspective view of a transformer and housing mounted upon a base structure in accordance with my invention, one sidewall being removed to show the internal mounting structure.

Referring now to the drawing and first to FIG. 1, I have illustrated by way of orientation a typical prior art transformer of the ventilated dry-type mounted upon a concrete base. The transformer comprises a core 1 and winding 2 disposed within a housing 3 and the whole is mounted upon a massive, rigid foundation 4. The foundation 4 is, for example, formed of concrete and is 3,312,920 Patented Apr. 4, i967 cross channel 5, all lying in flatwise contact with the upper surface of the foundation 4 and disposed substantially in the plane of the open end of the housing 3. The transformer core 1 rests'up-on and is fastened to a metal cross bar 6 which extends beyond the core at both sides and rests upon the base channel 5. Preferably, as shown in FIG. 1, there is interposed between the cross bar 6 and the base channel 5 a plurality of compression or bearing plates or pads 7 and 8 which may be formed, as desired, of steel or of a more resilient material such as rubber or other suitable elastomer. The cross bar 6 is fixed against lateral displacement by means of a pair of positioning pins 9 extending upwardly from the channel 5.

It would appear from the structure described at FIG .1 that the base channel member 5 is placed in compression only and should therefore transmit very little vibration from the core 1 and cross bar 6 to the housing walls 3a and 3b. The fact is, however, that in microscopic dimension neither the upper surface of the foundation nor the lower surface of the base channel 5 is entirely flat; each consists of a plurality of protruding points and ultimate engagement between the two actually takes place at only three points or more on the base 4, with a minimum of two points in any straight line. This is indicated, for example, at points a and b, FIG. 1, where it may be assumed that the channel 5 engages the base 4 While it is very slightly spaced therefrom at other locations. A departure from flatness as large as .025" would not be uncommon in either foundation or base channel. It will therefore be evident that the core assembly can transmit vibration to the base channel 5 at points between the support pins a and b, and therefore flex the cross beam by displacements which may be of significant magnitude. For example, displacements along the line 3 indicated at FIG. 1 on the channel 5 are usually significant if greater than .002. Such lateral flexing of the channel 5 will of course cause vertical movement of its outer ends and this vertical movement, perhaps amplified by the location of the pivot points a and b, is readily transmitted to the sidewalls 3a and 3b.

Referring now to FIG. 2, I have shown therein an improved noise-suppressing support embodying my invention. Those parts at FIG. 2 corresponding to like parts at FIG. 1 have been assigned the same reference numerals. FIG. 2 shows an open dry-type transformer including a magnetizable core 1 and a winding 2 disposed in a housing 3. As at FIG. 1 the housing 3 has an open bottom end and is fixed to base side channels 10 and 11 which rest directly upon a massive rigid foundation 4. In the assembly shown at FIG. 2, however, the transverse base channel 5 is displaced inwardly and upwardly from the plane of the open bottom of the housing thereby to connect the sidewalls 3a and 3b together at a location offset inwardly from the plane of the open end of the housing and thus above and out of contact with the foundation 4. Additional transverse base channels, not shown, may be fixed to the upper flanges of the inwardly facing U-shaped side channels 10 and 11.

At FIG. 2 the magnetizable core 1 is provided with a plurality of elongated supporting legs 12 which may be formed in pairs as flat extensions of side plates 13 between which the core laminations are clamped. The legs 12 are preferably of appreciable length and diverge downwardly and outwardly and thus aid in absorbing vibration of the massive core and coil structure. The lower ends of the legs 12 are bent outward to form a pair of mounting feet 14 and are connected together by a transverse metal strap or cross bar 6. The cross bar 6 is preferably formed of flat steel plate so that it may, if desired, be subjected to shear or bending stress and thereby further contribute by spring action to absorption of the core vibration. The cross bar 6 rests upon a pair of bearing blocks or pads 7a and 8a interposed directly between the cross bar 6 and the massive rigid foundation 4. No fixed, rigid or bearing connetcions exist between the cross bar 6 and the housing structure, but the outwardly extending ends of the bar 6 beyond the mounting feet 14 are loosely coupled to the housing structure by means of a pair of slidable positioning pins 9 Conveniently, the positioning pins 9 may be fixed in the lower flanges of the stiffening beams and 11 along the lower edges of the side panels 3a and 3b.

The compression plates or pads 70 and 8a may, if desired, be formed of steel or other relatively rigid material. Preferably, however, they are made of an appreciably resilient elastomeric material such as rubber. The compressional resilience of the bearing plates 7a and 8a is an element in the absorption and isolation of vibration originating in the core 1. In addition to providing compressional resilience in themselves, the plates 7a and 8a may be positioned in various locations along the length of the cross bar 6 to provide a desired amount of spring action in the bar 6. As shown in the drawing, rubber pads 7a and 8a are symmetrically positioned between and equally inwardly displaced from the mounting feet 14. It will be understood of course that if the pads 7a and 8a are located directly beneath the mounting feet 14, no shearing stress is applied to the cross bar 6 and no advantage is taken of its spring action.

It will now be understood from consideration of FIG. 2 that the resilient mounting structure there shown comprising the supporting legs 12, the spring action across bar 6 and the resilient compression pads 7a and 8a, serve effectively to absorb severe vibrations originating in the core 1. Whatever vibration is transmitted through this mounting structure is isolated from the enclosure 3 by the massive rigid character of concrete foundation 4, there being no fixed, rigid or bearing connections between any of the transformer supporting structure and the housing structure.

The apparatus illustrated at FIG. 2 thus comprises an induction apparatus and a housing separately set upon the foundation 4 to minimize vibration and noise in the housing. For the purpose of lifting and shipping, however, it is desirable that all components be fixedly connected together. This is readily accomplished by reason of the fact that the cross bar 6 overlaps the lower flanges of the channels 10 and 11, being loosely positioned thereon in operation by the pins 9. When it is desired to fix the housing and core together for shipment or other movement it is only necessary to remove the bearing pads 7a and 8a, lower the cross bar 6 to rest upon the channels it and 11, and bolt the cross bar and channels together. For this purpose pins 9 may be threaded, as shown, and provided with fastening nuts as illustrated at FIG. 1.

While I have illustrated a preferred embodiment of my invention and described it in considerable detail by way of illustration, various modifications will occur to those skilled in the art, and I therefore wish to :have it under stood that I intend in the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an electrical induction apparatus adapted to be mounted upon a massive rigid foundation having a substantially flat bearing surface, a housing having sidewalls of sheet material and an open base portion adapted to rest directly upon said foundation, a magnetizable core in said housing subject to severe vibration in operation, a pair of supporting legs extending downwardly toward said open base portion of said casing and terminating at their lower ends in spaced-apart mounting feet, a cross bar connected between said mounting feet in substantially parallel spaced relation with said bearing surface, said mounting feet and legs transmitting appreciable vibration from said core to said cross bar, a bearing plate interposed directly between said cross bar and said bearing surface thereby to support said core on said massive foundation free of any bearing contact with said housing, said bearing plate being offset from said mounting feet, and positioning means loosely connecting said cross bar to said sidewalls.

2. In an electric induction apparatus adapted to be mounted upon a massive rigid foundation having a substantially flat upper bearing surface, a housing having sidewalls of sheet material defining an open bottom end and adapted to rest directly upon said foundation, a magnetizable core in said housing subject to severe vibration in operation, a pair of supporting legs fixed to said core and diverging downwardly toward the open bottom end of said casing to form at their lower ends a pair of mounting feet, a cross bar connected between said mounting feet in substantially parallel spaced relation with said bearing surface, said supporting legs transmitting appreciable vibration from said core to said cross bar, a pair of spacedapart bearing plates interposed directly between said cross bar and said massive foundation thereby to support said core on said foundation free of any bearing contact with said housing, and means for fixedly positioning said cross bar with respect to said sidewalls without transmitting appreciable vibration therebetween.

3. An assembly according to claim 2 wherein said bearing plates include at least a single pair of plates positioned adjacent to but symmetrically offset from said mounting feet.

4. An assembly according to claim 2 in which the spaced-apart bearing plates comprise a single pair of elastomeric pads.

5. An assembly according to claim 3 in which the bearing plates comprise a single pair of spaced-apart resilient pads positioned between and symmetrically spaced from said mounting feet.

6. An assembly according to claim 1 wherein said bearing plate is shorter than the space between said mouting feet and is positioned therebetween.

7. An assembly according to claim 1 including, in addition, means independent of said core and cross bar for tying opposite pairs of sidewalls together at points spaced above said foundation.

3/1948 Werner 248-20 

1. IN AN ELECTRICAL INDUCTION APPARATUS ADAPTED TO BE MOUNTED UPON A MASSIVE RIGID FOUNDATION HAVING A SUBSTANTIALLY FLAT BEARING SURFACE, A HOUSING HAVING SIDEWALLS OF SHEET MATERIAL AND AN OPEN BASE PORTION ADAPTED TO REST DIRECTLY UPON SAID FOUNDATION, A MAGNETIZABLE CORE IN SAID HOUSING SUBJECT TO SEVERE VIBRATION IN OPERATION, A PAIR OF SUPPORTING LEGS EXTENDING DOWNWARDLY TOWARD SAID OPEN BASE PORTION OF SAID CASING AND TERMINATING AT THEIR LOWER ENDS IN SPACED-APART MOUNTING FEET, A CROSS BAR CONNECTED BETWEEN SAID MOUNTING FEET IN SUBSTANTIALLY PARALLEL SPACED RELATION WITH SAID BEARING SURFACE, SAID MOUNTING FEET AND LEGS TRANSMITTING APPRECIABLE VIBRATION FROM SAID CORE TO SAID CROSS BAR, A BEARING PLATE INTERPOSED DIRECTLY BETWEEN SAID CROSS BAR AND SAID BEARING SURFACE THEREBY TO SUPPORT SAID CORE ON SAID MASSIVE FOUNDATION FREE OF ANY BEARING CONTACT WITH SAID HOUSING, SAID BEARING PLATE BEING OFFSET FROM SAID MOUNTING FEET, AND POSITIONING MEANS LOOSELY CONNECTING SAID CROSS BAR TO SAID SIDEWALLS. 